Cognitive Impairment in Aging: 10 Common Causes & 10 Things the Doctor Should Check

Have you been worried about an older person’s memory or thinking abilities?

Maybe your parent has seemed more confused recently. Or you may have noticed that your aging spouse is repeating herself, or struggling to do things that didn’t use to pose much of a problem.

These are very common concerns, and they often lead to questions such as:

  • Is this normal aging or something more significant?
  • What is wrong?
  • Could this be Alzheimer’s? Or some other form of dementia?
  • Can this be treated or reversed?
  • What should we do about this??

The answer to the last question is this: if you are worried about memory or thinking, then you should seek out some kind of medical evaluation.

That’s because when families worry about an older person’s cognitive abilities, there often are some underlying health issues affecting the mind’s function.

Those need to be detected, and treated if at all possible. So, you’ll need to request help from a health professional, and in this article, I’ll explain what that initial help should consist of. This way you’ll know what to expect, and what the doctor might ask you about.

Technically, these kinds of problems are called “cognitive impairment.” This is a broad term that means some kind of problem or difficulty with one’s memory, thinking, concentration, and other functions of the conscious brain, beyond what might be expected due to normal “cognitive aging.”

(For more on “cognitive aging” and what types of changes are considered normal aging, see this article: 6 Ways that Memory & Thinking Change with Normal Aging, & What to Do About This.)

Cognitive impairment — which is also called “cognitive decline” — can come on suddenly or gradually, and can be temporary or more permanent. It may or may not keep getting slowly worse; it all depends on the underlying cause or causes.

In this article, I’ll share with you the more common causes of cognitive impairment in older adults.

I’ll then share a list of 10 things that should generally be done, during a preliminary medical evaluation for cognitive decline in an older adult.

You can also watch a subtitled video version of this information below.

Common causes of cognitive impairment in older adults


Cognitive impairment, like many problems in older adults, is often “multifactorial.” This means that the difficulties with memory, thinking, or other brain processes are often due to more than one cause.

Common causes of cognitive impairment in older adults include:

  • Medication side-effects. Many medications interfere with proper brain function.
  • “Metabolic imbalances.” This term refers to abnormalities in one’s blood chemistry.
    • Examples include abnormal levels of blood sodium, calcium, or glucose.
    • Kidney or liver dysfunction can also cause certain types of metabolic imbalances, and these sometimes affect brain function.
  • Problems with hormones, such as thyroid hormones.
    • Imbalances in estrogen and other sex hormones may also affect cognitive function.
  • Deficiencies in vitamins and other key nutrients.
    • Brain function is especially known to be affected by low levels of vitamin B12, other B vitamins, and folate.
  • Delirium. This is a state of worse-than-usual mental function that can be brought on by just about any type of serious illness.
    • Delirium is very common in hospitalized older adults, and can also occur due to infection or other health problems in older people who are not hospitalized.
  • Psychiatric illness. Most psychiatric conditions can cause problems with memory, thinking, or concentration. Psychiatric illnesses can also cause paranoia and other forms of late-life psychosis.
    • Depression and anxiety are probably the most common psychiatric conditions in older adults.
    • It is also possible for older adults to have bipolar disorder, schizophrenia, or other forms of major mental illness; these have often been diagnosed earlier in life.
  • Substance abuse and/or substance withdrawal.
    • Both acute intoxication and chronic overuse of certain substances (such as alcohol, illicit drugs, or even prescription drugs) can impair brain function.
  • Damage to brain neurons, due to an injury.
    • “Vascular” damage to neurons means damage caused by problems with the blood vessels, such as strokes or some form of cerebral small vessel disease.
    • Head injuries are also associated with temporary or longer-lasting cognitive impairment.
  • Damage to brain neurons, due to a neurodegenerative condition.
    • Neurodegenerative conditions tend to slowly damage and kill neurons. This can cause mild cognitive impairment, and then eventually dementia.
    • The more common neurodegenerative conditions include Alzheimer’s disease, Lewy-Body disease, Parkinson’s disease, and frontotemporal degeneration.
  • Infections.
    • This is not as common in older adults as the other causes above, but certain chronic or acute infections can affect brain cells directly. (If cognitive impairment is caused by an infection outside the brain, such as pneumonia or a urinary tract infection, this would be considered delirium.)

Toxins are another potential cause of cognitive impairment. Research is ongoing as to the cognitive effects of toxins people may be exposed to, such as heavy metals, air pollutants, contaminants in our drinking water, pesticides, and others.

Now that I’ve covered the most common causes of cognitive impairment in older adults, here’s what an initial medical evaluation should generally cover.

10 Things the Doctor Should Do When Evaluating Cognitive Impairment in an Older Adult

Here are ten specific things the clinician should ask about, check on, or do, as part of an initial evaluation for cognitive impairment in an older adult.

The following list reflects my own practice and that of most geriatricians. It is in line with most syntheses of guidelines and best practices, including the chapter on this subject.

Most experts agree that these steps can be done by primary care clinicians.

1. Ask about and document the patient’s concerns about memory and thinking.

At a minimum, the clinician should ask an older person something like “So, have you noticed any changes in your memory or thinking abilities?”

Now, many older adults will either have noticed nothing or won’t want to talk about it. This is in of itself worth noting, especially if family or others have voiced concerns.

If the older person does have concerns or observations, these should be explored. It’s especially important to ask when the problems started, whether they seem to be getting worse, and how quickly things seem to be changing.

2. Obtain or request information on memory or thinking difficulties from family members or other “informants.”

Older adults with cognitive impairment are often unaware of — or reluctant to reveal – the difficulties they are experiencing. For this reason, a health provider who has been alerted to the possibility of cognitive impairment should make an effort to get information from a family member or other knowledgeable informant.

The best is to ask a family member to complete a validated questionnaire, such as the AD-8 informant interview. (This questionnaire asks about 8 behaviors that may indicate a dementia such as Alzheimer’s disease.)

It’s sometimes necessary for the health provider to be diplomatic about requesting and getting information from family members, especially if the older person finds it upsetting. People may think that HIPAA doesn’t allow doctors to talk to family over an older person’s objections, but actually, clinicians do have some leeway in these situations. (See my HIPAA article here.)

Family members can facilitate this process by bringing in a written summary of what difficulties they’ve observed. Be sure to include information on when the problems started and whether they seem to be getting worse.

3. Ask about difficulties managing instrumental activities of daily living (IADLs) and activities of daily living (ADLs).

The ideal is for the health provider to ask both the patient and the family about this. Older adults with cognitive impairment are often not reliable reporters of what difficulties they’re having.

Instrumental activities of daily living (IADLs), in particular,  are often affected by cognitive impairment. So it’s important to ask if the older person is having difficulty with problems with tasks such as:

  • Driving and other forms of transportation
  • Management of finances
  • Grocery shopping and meal preparation
  • Home maintenance
  • Managing the telephone, the mail, and other forms of communication
  • Medication management

The provider should also ask about ADLs, which are the more fundamental self-care tasks such as walking around, feeding oneself, getting dressed, managing continence, and so forth.

You can learn more about ADLs and IADLs here: What are Activities of Daily Living (ADLs) & Instrumental Activities of Daily Living (IADLs)?

Difficulties with IADLs and ADLs (which geriatricians refer to as “functional impairment”) are important to document. They offer a practical lens on how “severe” an older person’s cognitive impairment might be, and on what steps could be taken to support an older person while these cognitive issues are getting evaluated.

Functional impairments may correspond with safety issues that need to be addressed; if an older person is having difficulty with finances, it may be a good idea to check for signs of financial exploitation, or otherwise take steps to protect the person financially.

Last but not least, impairment in daily functioning is also a criterion that separates mild cognitive impairment (MCI) from more significant impairment (including dementia). In MCI, a person may be experiencing some cognitive impairment, but it should not be bad enough to significantly interfere with performing their usual daily life tasks.

4. Check for the presence of other behavioral, mood, and thinking symptoms that may be related to certain causes of cognitive impairment.

These include:

  • Hallucinations
  • Delusions
  • Personality changes
  • Apathy (losing motivation)
  • Depression symptoms
  • Anxiety symptoms
  • Getting lost
  • Confusion about visual-spatial tasks (e.g. having difficulty figuring out how to put on one’s shirt)

5. Ask about any new symptoms or changes in physical health.

It’s especially important to ask about symptoms related to neurological function, such as new difficulties with walking, balance, speech, and coordination. Checking for tremor and stiffness (both of which are associated with Parkinsonism) is also recommended.

The exact questions the clinician asks will depend on the person’s particular medical history, and the other signs and symptoms that have been brought up.

6. Ask about substance use and consider the possibility of substance abuse and/or withdrawal.

Excessive use of alcohol, certain prescription drugs (such as tranquilizers), or of illicit drugs can affect cognitive function. Health providers should inquire about an older person’s use of these substances.

Suddenly stopping or reducing the use of alcohol or other substances can also occasionally cause or worsen cognitive function.

7. Review all medications, with a focus on identifying those known to worsen cognitive function.

Certain types of medications tend to dampen brain function, and may cause a noticeable worsening in cognitive abilities. The health provider should especially ask about use of:

  • Benzodiazepines, which are often prescribed for either insomnia or anxiety
    • Commonly prescribed benzodiazepines include lorazepam, diazepam, temazepam, alprazolam (brand names Ativan, Valium, Restoril, and Xanax, respectively)
  • Prescription sleeping pills, such as zolpidem (brand name Ambien)
  • Anticholinergics, a broad category of medications which includes most over-the-counter sleeping aids, sedating antihistamines, drugs for overactive bladder, muscle relaxants, and others.

For more on medications that affect brain function, see 4 Types of Medication to Avoid if You’re Worried About Memory.

8. Perform a physical examination.

At a minimum, the health provider should check vitals (blood pressure and pulse) and should also complete a basic neurological evaluation, including an observation of the person’s gait, balance, and coordination.

The purpose of the physical exam is to look for physical signs that may correspond to causes of cognitive impairment, or that may relate to other symptoms the patient or family brought up.

9. Assess the person’s orientation and perform some type of office-based cognitive test.

Assessing “orientation” means checking to see whether the patient knows things like the day, date, month, year, and where he or she is.

Some office-based testing should also be done, to check and document the older person’s memory and thinking abilities.

Probably the shortest well-validated test is the Mini-Cog, which involves a three-item recall and a clock draw.

A more detailed office-based cognitive test that can be done in primary care is the MOCA test (Montreal Cognitive Assessment Test). This takes 10-20 minutes to administer, so it often requires scheduling a separate visit.

There are some other “intermediate” length tests that can be done in the primary care office, such as the SLUMS (St. Louis University Mental Status Examination). The Mini-Mental State Exam is another option, although most experts (including myself) consider it less useful than the MOCA or SLUMS.

10. Order laboratory testing (unless recently done) and consider brain imaging.

In most cases, it will be appropriate for the health provider to order blood tests, to check for common health problems that can cause or worsen cognitive impairment.

Blood tests to consider include:

  • A complete metabolic panel, which assesses electrolytes, kidney function, and liver function tests
  • Vitamin B12
  • Thyroid function tests

Additional tests, such as a complete blood count,  may be ordered as well, depending on the person’s past medical history, current symptoms, and risk factors. For more on tests that are often ordered in older adults, see Understanding Laboratory Tests: 10 Commonly Used Blood Tests for Older Adults.

As for brain imaging, some expert guidelines recommend it for everyone and other guidelines suggest it be used “selectively.”

(In most cases, brain imaging reveals non-specific findings such as signs of cerebral small vessel disease and perhaps some mild atrophy of the brain. These are common findings in many older adults and tend to have a variable correlation with symptoms. Most causes of cognitive impairment cannot be definitely ruled in or ruled out by brain imaging.)

In Summary

Overall, an initial medical evaluation should result in these four key things happening:

  • Documentation of the patient’s and family’s cognitive concerns.
    • This means documenting what the patient and family have noticed, in terms of difficulties and changes in memory, thinking, behavior, or personality.
  • Documentation of any functional impairment the older person is experiencing.
    • This means documenting what the patient and family have noticed, in terms of difficulties managing life tasks (IADLs and ADLs).
  • An objective assessment of the older person’s memory and thinking skills.
    • This best done through some form of short standardized office-based test, such as the Mini-Cog.
    • Clinicians can also document their impressions and observations based on talking to the older person. (Did the person seem confused? Paranoid? Repetitive? Tangential? Was the person able to answer detailed questions?)
  • An evaluation for common medical causes and contributors of cognitive impairment.
    • This means checking for those common problems that can cause or worsen cognitive impairment.

Generally, it will take at least two primary care visits to complete an evaluation for cognitive impairment.

The second visit is often used to do a cognitive test such as the MOCA, and can enable the clinician to follow up on laboratory tests that were initially ordered.

And then what?

Well, what happens next depends on several things, such as:

  • Whether the health provider was able to draw conclusions about what is likely causing the cognitive impairment
  • Whether treatable conditions were identified
  • How the patient and family feel about the evaluation
  • Whether the older person is willing and able to cooperate
  • Whether the clinician feels that referral to a specialist is necessary
  • Whether the clinician is willing and able to help the older person and the family (or refer them for help) addressing any functional impairment or safety issues

You may be wondering: should you expect a diagnosis or “an answer” after this evaluation?

I’ll be honest here: probably not. Even with an adequate initial evaluation, cognitive impairment may take a few months (or even longer) to completely evaluate and diagnose. For instance, it’s often necessary to try treating one or more potential causes, to see if the cognitive problems improve or not.

Other causes of cognitive decline — notably neurodegenerative conditions such as Alzheimer’s and some of the other dementias — can take a while to diagnose because clinicians are first supposed to exclude the other potential causes, and that can take a while. (For more on the diagnosis of dementia, see “How We Diagnose Dementia: The Practical Basics to Know.)

What to expect from an initial evaluation for cognitive decline

It may not be realistic to expect definite answers. But that doesn’t mean you can’t expect some explanations.

Your health provider should be able to explain:

  • How substantial the cognitive impairment appears to be, based on the office-based testing and the evaluation so far,
  • What was checked for, and what has been ruled out (or deemed unlikely) as a cause for the problems you’ve been worried about,
  • Whether any of the medications might be making memory or thinking worse, and what the options are for stopping or reducing those medications,
  • What the healthcare team proposes to do next, to further evaluate the issues or follow up on the problems.

So if you’ve been worried about memory or thinking problems, ask for that medical evaluation. If your health provider skips any of the steps I listed, don’t be shy and ask about it. (Either it’s an oversight or they should be able to explain why it’s not necessary.)

You probably won’t get all the answers and certainty that you’re hoping for, but you’ll have gotten started and that’s vitally important.

Of course, you may well be facing the problem of not being able to get your older loved one to go to the doctor. That’s a very common issue, but it’s too complicated to cover in an article. (So I’ve written a book! You can find it here.)

In the meantime, especially if it’s a challenge to see the doctor for some reason, then it’s all the more important to the most out of your medical evaluation when you do manage to get there.

This article was originally published in 2018, and was last reviewed by Dr. Kernisan in Dec 2021.